BIOL 120 - The Lac Operon Lab Quiz Terms

lacO

An operator site that is involved in the transcriptional regulation of the lac operon.

operator

On/ off switch turns operon on or off activated by lac repressor

lacZ

One of 3 structural genes. an intracellular enzyme that cleaves the disaccharide lactose into glucose and galactose. encodes β-galactosidase

promoter

Region of DNA where RNA polymerase can grab onto the DNA a region of DNA that initiates transcription of a particular gene

catabolite activator protein (CAP)

a DNA binding protein involved with the transcription of several genes, including those that code for enzymes involved in the metabolism of certain sugars.

lac repressor

a DNA-binding protein which inhibits the expression of genes coding for proteins involved in the metabolism of lactose in bacteria.

ONPG

a colorimetric and spectrophotometric substrate for detection of β-galactosidase activity

regulatory gene

a gene involved in controlling the expression of one or more other genes may encode a protein, or it may work at the level of RNA

inducer

a molecule that regulates gene expression can bind to protein repressors or activators function by disabling repressors

cAMP

a second messenger a derivative of adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms

glucose

a simple sugar that is an important energy source in living organisms and is a component of many carbohydrates.

lactose

a sugar present in milk. It is a disaccharide containing glucose and galactose units.

inducible operon

are an example of negative control of gene expression. Their default state is "off", meaning that binding of the active regulator protein to DNA, thereby blocking transcription initiation, is the default state.

RNA polymerase

codes for genes An enzyme that catalyzes the synthesis of an RNA strand from a DNA template

lac operon

designed for e coli to break down or deal with lactose.

beta-galactosidase

glycoside hydrolase enzyme that catalyzes the hydrolysis of β-galactosides into monosaccharides through the breaking of a glycosidic bond

lacI

lac repressor in lac operon negative inducible regulation - gene is turned off by lac repressor unless lactose is present

transcription

the first step of gene expression, in which a particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase